Chapter 4: Sever
After listening to Miwa explain several fundamental techniques of cursed energy control, Ren immediately felt the difference.
His cursed energy manipulation had become noticeably more efficient.
Using less cursed energy, he could now produce a stronger effect. When he gathered cursed energy into his fists, he could clearly sense that they were even more powerful than his previous "twelve-times-normal punches."
That said, given the previous lessons, he hesitated to test it recklessly.
"It's fine."
Sensing his hesitation, Utahime Iori bit her lip slightly. Inwardly, she quietly reclassified the extra equipment expenses under "recruitment costs."
"Go ahead and try, Ren."
"We're going to replace all these training tools with newer, sturdier ones anyway. These old ones were scheduled for disposal."
Ren nodded. With the teacher herself saying so, he had no more reservations.
He strode forward a few steps and drove a punch into another sandbag.
BOOM!
The sandbag detonated once again. Sand poured down from the sky like a sudden rainstorm.
Thankfully, this time, everyone had learned their lesson and instinctively protected themselves with cursed energy.
Otherwise—judging by the force carried by the flying sand—Utahime estimated that even the debris alone would have been enough to tear skin and draw blood.
What terrifying power.
Ren shook his fist thoughtfully.
Punching alone wasn't enough.
Glancing at the few remaining sandbags, he decided to test other aspects of his abilities.
He concentrated cursed energy into his legs and kicked off the ground.
BOOM!
His body shot forward like a cannonball, only coming to a stop at the far end of the training field.
"Sensei,"
his voice called out from across the field,
"is the training ground okay too?"
Utahime lowered her head.
She looked at the field—at the massive crater torn open beneath Ren's takeoff point, the turf and earth blasted apart, spiderweb-like cracks spreading outward across the ground—and felt a sharp pain in her heart.
Still, she forced herself to raise her fair, composed face and smile brightly at him.
"No problem at all, Kanzaki-kun!"
"Kyoto Jujutsu High exists precisely to train students like you."
"So please—make full use of everything here and train to your heart's content!"
"Got it!"
The boy answered cheerfully.
A moment later—
BOOM!
Like a human artillery shell, he launched himself back across the field. Soil, gravel, and torn grass exploded outward on impact, the violent tremor nearly knocking Utahime off her feet.
Next, the group could only stand there and watch as the boy continued bounding back and forth across the field—leaping, punching, kicking. Gravel flew everywhere, dirt rained down, and in no time at all the training ground was left riddled with craters and scars.
"Ren… is amazing," Kasumi Miwa murmured to herself, staring at the figure darting through the choking dust and smoke.
Many of the techniques she had just taught him were things she herself had only fully mastered after long periods of thought and painstaking practice. She had assumed he would stumble somewhere—hesitate, struggle, show at least some awkwardness.
But from beginning to end, the boy showed none of that.
He had merely listened once—and then used everything flawlessly.
At this point, his cursed energy control already resembled that of a formal New Shadow Style practitioner.
Before she could fully process that—
The boy flashed toward her in a blur and stopped right beside her.
"Miwa," Ren asked straightforwardly,
"are there any other techniques you can teach me? Everything you have."
Since this was a school and not a rigid, tradition-bound dojo, he felt no hesitation in asking freely.
The techniques Miwa had taught him were genuinely useful. Naturally, that sparked an even stronger desire to keep learning.
He knew that if he tried to figure everything out on his own, he would eventually succeed—but it would take far more time.
"Other… techniques?"
Miwa was stunned.
On one hand, she hadn't expected his learning speed to be so terrifying that he'd already be asking for more. On the other, she had already taught him all the foundational cursed energy control techniques she knew.
Anything beyond that…
She did possess some advanced skills—such as Simple Domain—but those were closely guarded secrets of the New Shadow Style, not something she could casually teach to someone outside the school of transmission.
"I feel like there's still a lot of room for optimization," Ren said to himself.
Ever since Miwa had opened the door to cursed energy control for him, new ideas had been constantly bursting forth in his mind.
"For example—"
He raised one hand.
A faint blue glow gathered along the edge of his palm—cursed energy so dense it was visible to the naked eye.
Before anyone could react—
He swung his hand.
The blue light shot forward, carving a long, blade-like trail through the air.
CRACK!
In the next instant, the wire fence surrounding the field was ripped apart. Beyond it, towering trees snapped cleanly at the waist. Only after slicing through seven or eight trees over dozens of meters did the blue blade finally dissipate into the air.
"Th-th-th-this is…?!"
Miwa stared at the scene, completely dumbfounded, her tongue practically tied in knots.
Compressing cursed energy directly into a solid blade—that was a technique only high-level instructors of the New Shadow Style could use!
Even Miwa herself, despite her diligence, had never mastered it. At best, she could only attach cursed energy to existing cursed tools—like the katana at her waist—to enhance them.
And according to everything she knew, even within the New Shadow Style, such "cursed energy blades" were meant to be held, wielded as sharper swords.
But this boy—
Not only could he create such a blade…
He had fired it like a projectile.
H-how was that even possible?!
"W-what technique is that?" she blurted out.
"That counts as a 'technique'?"
Ren looked genuinely surprised.
"Isn't it just basic cursed energy manipulation?"
"If you really want to call it something," he added casually,
"then let's name it 'Sever.'"
…So perfunctory, Miwa thought weakly.
But that casual naming said everything—this terrifying move truly wasn't difficult for him.
"I've noticed that directly reinforcing the body with cursed energy is very effective," Ren continued.
"But in some situations, having ranged options to diversify your tactics is also useful."
"So I thought—why not compress cursed energy into a blade and fire it directly?"
"B–But how did you launch it?" Miwa asked in disbelief.
"Just use cursed energy as the propulsion," he replied matter-of-factly.
Miwa froze.
Using cursed energy as propulsion—how exactly did that work? He made it sound trivial, but no matter how hard she thought, she couldn't grasp the mechanism.
And yet, judging from his expression, this was as natural to him as fish swimming or birds flying.
"Of course," Ren went on,
"this was only a preliminary attempt."
"There are definitely techniques to optimize both the blade's formation and its propulsion—ways to make it sharper, faster, more lethal."
"So… could you help guide me on that, Miwa?"
Miwa stared at the boy before her—eyes shining, eager to learn.
Large beads of sweat rolled down from her small forehead.